Blockchain declarative descriptor for cross-network communication

ABSTRACT

An example operation may include one or more of retrieving decentralized identifiers (DIDs) of a plurality of blockchain peers included within a blockchain network, generating a blockchain declarative descriptor (BDD) which uniquely identifies the blockchain network, where the BDD comprises a machine-readable data file with a first field includes the retrieved DIDs of the blockchain network, a second field including signature data of the plurality of blockchain peers, and a third field including metadata, and transmitting the generated BDD to a blockchain network registry.

BACKGROUND

A centralized platform stores and maintains data in a single location.This location is often a central computer, for example, a cloudcomputing environment, a web server, a mainframe computer, or the like.Information stored on a centralized platform is typically accessiblefrom multiple different points. Multiple users or client workstationscan work simultaneously on the centralized platform, for example, basedon a client/server configuration. A centralized platform is easy tomanage, maintain, and control, especially for purposes of securitybecause of its single location. Within a centralized platform, dataredundancy is minimized as a single storing place of all data alsoimplies that a given set of data only has one primary record.

SUMMARY

One example embodiment provides an apparatus that includes a networkinterface configured to retrieve decentralized identifiers (DIDs) of aplurality of blockchain peers included within a blockchain network, anda processor configured to one or more of generate a blockchaindeclarative descriptor (BDD) which uniquely identifies the blockchainnetwork, where the BDD comprises a machine-readable data file with afirst field that includes the retrieved DIDs of the blockchain network,a second field that includes signature data of the plurality ofblockchain peers, and a third field that includes metadata, and transmitthe generated BDD to a blockchain network registry.

Another example embodiment provides a method that includes one or moreof retrieving decentralized identifiers (DIDs) of a plurality ofblockchain peers included within a blockchain network, generating ablockchain declarative descriptor (BDD) which uniquely identifies theblockchain network, where the BDD comprises a machine-readable data filewith a first field includes the retrieved DIDs of the blockchainnetwork, a second field including signature data of the plurality ofblockchain peers, and a third field including metadata, and transmittingthe generated BDD to a blockchain network registry.

A further example embodiment provides a method that includes one or moreof querying a network registry for a blockchain declarative descriptor(BDD) of a first blockchain network, the BDD comprising a networkstructure and identifiers of a plurality of peers of the firstblockchain network, retrieving a decentralized identifier (DIDs) of apeer of the first blockchain network from the first blockchain network,verifying the peer of the first blockchain network based on a comparisonof the retrieved DID of the entity and the identifiers of the pluralityof peers included in the BDD, and in response to successfulverification, transmitting an inter-network communication from a peer ina second blockchain network to the peer in first blockchain network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram illustrating a communication environment thatincludes multiple blockchain networks according to example embodiments.

FIG. 1B is a diagram illustrating a blockchain declarative descriptor(BDD) according to example embodiments.

FIG. 2A is a diagram illustrating an example blockchain architectureconfiguration, according to example embodiments.

FIG. 2B is a diagram illustrating a blockchain transactional flow amongnodes, according to example embodiments.

FIG. 3A is a diagram illustrating a permissioned network, according toexample embodiments.

FIG. 3B is a diagram illustrating another permissioned network,according to example embodiments.

FIG. 3C is a diagram illustrating a permissionless network, according toexample embodiments.

FIG. 4A is a diagram illustrating a process of generating a BDD based onblockchain organization information according to example embodiments.

FIG. 4B is a diagram illustrating a process of verifying a BDD andperforming an inter-network communication according to exampleembodiments.

FIG. 5A is a diagram illustrating a method of generating a blockchaindeclarative descriptor according to example embodiments.

FIG. 5B is a diagram illustrating a method verifying a BDD andperforming an inter-network communication according to exampleembodiments.

FIG. 6A is a diagram illustrating an example system configured toperform one or more operations described herein, according to exampleembodiments.

FIG. 6B is a diagram illustrating another example system configured toperform one or more operations described herein, according to exampleembodiments.

FIG. 6C is a diagram illustrating a further example system configured toutilize a smart contract, according to example embodiments.

FIG. 6D is a diagram illustrating yet another example system configuredto utilize a blockchain, according to example embodiments.

FIG. 7A is a diagram illustrating a process of a new block being addedto a distributed ledger, according to example embodiments.

FIG. 7B is a diagram illustrating data contents of a new data block,according to example embodiments.

FIG. 7C is a diagram illustrating a blockchain for digital content,according to example embodiments.

FIG. 7D is a diagram illustrating a block which may represent thestructure of blocks in the blockchain, according to example embodiments.

FIG. 8A is a diagram illustrating an example blockchain which storesmachine learning (artificial intelligence) data, according to exampleembodiments.

FIG. 8B is a diagram illustrating an example quantum-secure blockchain,according to example embodiments.

FIG. 9 is a diagram illustrating an example system that supports one ormore of the example embodiments.

DETAILED DESCRIPTION

It will be readily understood that the instant components, as generallydescribed and illustrated in the figures herein, may be arranged anddesigned in a wide variety of different configurations. Thus, thefollowing detailed description of the embodiments of at least one of amethod, apparatus, non-transitory computer readable medium and system,as represented in the attached figures, is not intended to limit thescope of the application as claimed but is merely representative ofselected embodiments.

The instant features, structures, or characteristics as describedthroughout this specification may be combined or removed in any suitablemanner in one or more embodiments. For example, the usage of the phrases“example embodiments”, “some embodiments”, or other similar language,throughout this specification refers to the fact that a particularfeature, structure, or characteristic described in connection with theembodiment may be included in at least one embodiment. Thus, appearancesof the phrases “example embodiments”, “in some embodiments”, “in otherembodiments”, or other similar language, throughout this specificationdo not necessarily all refer to the same group of embodiments, and thedescribed features, structures, or characteristics may be combined orremoved in any suitable manner in one or more embodiments. Further, inthe diagrams, any connection between elements can permit one-way and/ortwo-way communication even if the depicted connection is a one-way ortwo-way arrow. Also, any device depicted in the drawings can be adifferent device. For example, if a mobile device is shown sendinginformation, a wired device could also be used to send the information.

In addition, while the term “message” may have been used in thedescription of embodiments, the application may be applied to many typesof networks and data. Furthermore, while certain types of connections,messages, and signaling may be depicted in exemplary embodiments, theapplication is not limited to a certain type of connection, message, andsignaling.

Example embodiments provide methods, systems, components, non-transitorycomputer readable media, devices, and/or networks, which are directed togenerating and verifying a blockchain declarative descriptor tofacilitate trusted cross-network communications among blockchainnetworks.

In the example embodiments, each blockchain entity (e.g., peers,orderers, endorsers, clients, auditors, admins, etc.) may be assigned aunique decentralized identifier (DID) that identifies the blockchainentity within a blockchain network. A blockchain entity that possesses aDID may also be issued one or more verifiable credentials (VCs) whichcan be used by the blockchain entity to sign blockchain transactions,messages, blocks, and the like. In some embodiments, each blockchainentity may include a set of VCs which give the blockchain entity a setof claims. A claim, for example, may be a claim that a blockchain peeris authorized to sign a transaction for a particular smart contract(chaincode). As another example, a claim may be that a blockchain peeris authorized to transact on a particular channel/blockchain among aplurality of channels on a blockchain ledger. As another example, aclaim may identity that the blockchain peer is an endorsing peer of theblockchain network, etc.

Each verifiable credential may be issued from an authority within aSelf-Sovereign Identity (SSI) SSI network of the blockchain network, forexample, a membership service provider (MSP), a certificate authority(CA), or the like. The verifiable credential may include “proof” such asa signature of the issuer of the verifiable credential. The SSI networkmay maintain all allocated DIDs, VCs, and the like. In addition, the SSInetwork may maintain schema information of each VC, a public key of theissuer that signed the public key, and the like. Members of theblockchain can access the registry to obtain the schema information andthe public key of the issuer to verify the schema of the verifiablecredential and the signature of the issuer, respectively. In this way,any of the blockchain entities can validate the verifiable credentialwithout relying on a central authority.

To generate a blockchain declarative descriptor (BDD) according tovarious embodiments, the entities within a blockchain network mayaggregate their identification information (e.g., DIDs, VCs, etc.) intoa single verifiable credential (VC) that can be used to prove that anyof the entities are participants within the blockchain network. In thisway, the BDD is essentially a verifiable credential for the entireblockchain network. As an example, the BDD may include a claims field(e.g., data element) with a “network structure” embedded therein. Thenetwork structure may include a list of blockchain peers/organizationsidentified b their DIDs, chaincode names and peers that participate inthe chaincode, endorsing peers, and the like. The claims field may alsoinclude a network alterations clause that describes how a new member canbe added to the BDD and/or how an existing member can be removed fromthe BDD.

Furthermore, the proof section of the BDD may include a multi-signatureproof. Here, each blockchain peer/organization that is part of the BDDmay generate a signature over the claim field of the BDD. The signaturesmay be combined and stored together in the proof field of the BDD. TheBDD may be stored in a network registry that is available to multipleblockchain networks. Thus, any other network may identify the membershipof the blockchain network by the list of peers/organizations stored inthe claim field, and verify the membership of a particularpeer/organization based on the signatures stored in the proof field.

For example, when a first blockchain peer in a first blockchain networkdesires to communicate with a second blockchain peer in a secondblockchain network, the first blockchain peer (or another service of thefirst blockchain network) may query the network registry for the BDD ofthe second blockchain network. The first blockchain peer may also querya sentinel agent/program of the second blockchain network for networkinformation (e.g., a DID, VC, etc.) of the second blockchain peer. Here,the first blockchain peer may verify the second blockchain peer is amember of the second blockchain network based on a comparison of the DIDto the list of DIDs in the claim field, as well as a signature of thesecond peer included in the proof section of the BDD. Thus, trustedcommunications can occur even though both participants are on differentblockchain networks.

In one embodiment this application utilizes a decentralized database(such as a blockchain) that is a distributed storage system, whichincludes multiple nodes that communicate with each other. Thedecentralized database includes an append-only immutable data structureresembling a distributed ledger capable of maintaining records betweenmutually untrusted parties. The untrusted parties are referred to hereinas peers or peer nodes. Each peer maintains a copy of the databaserecords and no single peer can modify the database records without aconsensus being reached among the distributed peers. For example, thepeers may execute a consensus protocol to validate blockchain storagetransactions, group the storage transactions into blocks, and build ahash chain over the blocks. This process forms the ledger by orderingthe storage transactions, as is necessary, for consistency. In variousembodiments, a permissioned and/or a permissionless blockchain can beused. In a public or permission-less blockchain, anyone can participatewithout a specific identity. Public blockchains can involve nativecryptocurrency and use consensus based on various protocols such asProof of Work (PoW). On the other hand, a permissioned blockchaindatabase provides secure interactions among a group of entities whichshare a common goal but which do not fully trust one another, such asbusinesses that exchange funds, goods, information, and the like.

This application can utilize a blockchain that operates arbitrary,programmable logic, tailored to a decentralized storage scheme andreferred to as “smart contracts” or “chaincodes.”In some cases,specialized chaincodes may exist for management functions and parameterswhich are referred to as system chaincode. The application can furtherutilize smart contracts that are trusted distributed applications whichleverage tamper-proof properties of the blockchain database and anunderlying agreement between nodes, which is referred to as anendorsement or endorsement policy. Blockchain transactions associatedwith this application can be “endorsed” before being committed to theblockchain while transactions, which are not endorsed, are disregarded.An endorsement policy allows chaincode to specify endorsers for atransaction in the form of a set of peer nodes that are necessary forendorsement. When a client sends the transaction to the peers specifiedin the endorsement policy, the transaction is executed to validate thetransaction. After validation, the transactions enter an ordering phasein which a consensus protocol is used to produce an ordered sequence ofendorsed transactions grouped into blocks.

This application can utilize nodes that are the communication entitiesof the blockchain system. A “node” may perform a logical function in thesense that multiple nodes of different types can run on the samephysical server. Nodes are grouped in trust domains and are associatedwith logical entities that control them in various ways. Nodes mayinclude different types, such as a client or submitting-client nodewhich submits a transaction-invocation to an endorser (e.g., peer), andbroadcasts transaction-proposals to an ordering service (e.g., orderingnode). Another type of node is a peer node which can receive clientsubmitted transactions, commit the transactions and maintain a state anda copy of the ledger of blockchain transactions. Peers can also have therole of an endorser, although it is not a requirement. Anordering-service-node or orderer is a node running the communicationservice for all nodes, and which implements a delivery guarantee, suchas a broadcast to each of the peer nodes in the system when committingtransactions and modifying a world state of the blockchain, which isanother name for the initial blockchain transaction which normallyincludes control and setup information.

This application can utilize a ledger that is a sequenced,tamper-resistant record of all state transitions of a blockchain. Statetransitions may result from chaincode invocations (i.e., transactions)submitted by participating parties (e.g., client nodes, ordering nodes,endorser nodes, peer nodes, etc.). Each participating party (such as apeer node) can maintain a copy of the ledger. A transaction may resultin a set of asset key-value pairs being committed to the ledger as oneor more operands, such as creates, updates, deletes, and the like. Theledger includes a blockchain (also referred to as a chain) which is usedto store an immutable, sequenced record in blocks. The ledger alsoincludes a state database which maintains a current state of theblockchain.

This application can utilize a chain that is a transaction log which isstructured as hash-linked blocks, and each block contains a sequence ofN transactions where N is equal to or greater than one. The block headerincludes a hash of the block's transactions, as well as a hash of theprior block's header. In this way, all transactions on the ledger may besequenced and cryptographically linked together. Accordingly, it is notpossible to tamper with the ledger data without breaking the hash links.A hash of a most recently added blockchain block represents everytransaction on the chain that has come before it, making it possible toensure that all peer nodes are in a consistent and trusted state. Thechain may be stored on a peer node file system (i.e., local, attachedstorage, cloud, etc.), efficiently supporting the append-only nature ofthe blockchain workload.

The current state of the immutable ledger represents the latest valuesfor all keys that are included in the chain transaction log. Since thecurrent state represents the latest key values known to a channel, it issometimes referred to as a world state. Chaincode invocations executetransactions against the current state data of the ledger. To make thesechaincode interactions efficient, the latest values of the keys may bestored in a state database. The state database may be simply an indexedview into the chain's transaction log, it can therefore be regeneratedfrom the chain at any time. The state database may automatically berecovered (or generated if needed) upon peer node startup, and beforetransactions are accepted.

The example embodiments improve upon the security of cross-networkinteractions, where assets or data items are shared between permissionedblockchain ledgers. Participants (blockchain peers) can be authenticatedby an external party such as a blockchain peer on a different blockchainnetwork, using the BDD as described herein. Furthermore, portability andinteroperability may be improved. Permissioned networks today possesstheir own proprietary identity management systems (for credentialissuance and storage). This is not visible to parties outside thenetworks. By using BDD in place of these heterogeneous and opaqueidentity management systems, the example embodiments can ensure thatnetwork participants are known and can prove their authenticity outsidetheir networks, thereby allowing data and assets to flow across networkboundaries (in a policy-controlled way). Further, the BDD may be builtaround well-known identity providers or credential authorities such asmembership service providers (MSPs) and credential authorities (CAs)that are not tied to a specific network. This enables portability ofidentity and credentials in inter-network interactions.

In the example embodiments, verifiable credentials can be issued to DIDholders (network participants that rely on SSI). The verifiablecredentials can be issued by issuers (members of the SSI network) thatcan be existing identity providers and certificate authorities withinpermissioned networks or they can be well-known external authorities.Within networks, issuers may include network or organizational(sub-division) CAs. In a Hyperledger Fabric network, these entities arecalled MSPs (membership service providers), which maintain chains ofroot and intermediate CAs. In a Corda network, there is a hierarchy ofnetwork CAs credentialing doormen CAs who in turn credential node CAs(each node having the ability to sign and approve transactions.) TheseMSPs or CAs represent either a network as a whole or sub-divisionswithin a network, and they issue/revoke identities and credentials (suchas DIDs.) Outside of networks, the issuers may include external partiessuch as reputed CAs and credentialing authorities, like Verisign or theDMV. Other issuers can include existing organizations that choose toparticipate in a permissioned network, ad hoc authorities representingthe consortium of organizations that comprises a business network, forexample, a supply chain, a food trust network, etc. It should also beappreciated that the SSI networks are capable of managing identities ofmultiple networks' participants and facilitating identity-sharing acrossnetwork boundaries.

In the example embodiments, a participant such as a blockchain peer oran ordering service may be issued a DID. The DID may be a uniqueidentifier such as a URI that identifies the blockchain entity. Forexample, a DID enables verifiable, decentralized digital identity. A DIDidentifies any subject (e.g., a person, organization, thing, data model,abstract entity, etc.) that the controller of the DID decides that itidentifies. In contrast to typical, federated identifiers, DIDs havebeen designed so that they may be decoupled from centralized registries,identity providers, and certificate authorities. Specifically, whileother parties might be used to help enable the discovery of informationrelated to a DID, the design enables the controller of a DID to provecontrol over it without requiring permission from any other party. DIDsare URIs that associate a DID subject with a DID document allowingtrustable interactions associated with that subject.

Each DID document can express cryptographic material, verificationmethods, or services, which provide a set of mechanisms enabling a DIDcontroller to prove control of the DID. Services enable trustedinteractions associated with the DID subject. A DID document mightcontain the DID subject itself, if the DID subject is an informationresource such as a data model. This document may specify a common datamodel, a URL format, and a set of operations for DIDs, DID documents,and DID methods. A DID is a simple text string consisting of three partsincluding a URI scheme identifier (did), and identifier for the DIDmethod, and a DID method-specific identifier. DIDs are resolvable to DIDdocuments. A DID URL extends the syntax of a basic DID to incorporateother standard URI components (path, query, fragment) in order to locatea particular resource, for example, a public key inside a DID document,or a resource available external to the DID document.

DID documents contain information associated with a DID. They typicallyexpress verification methods (such as public keys) and services relevantto interactions with the DID subject. A DID document can be serializedaccording to a particular syntax. The DID itself is the value of the idproperty. The properties present in a DID document may be updated. DIDmethods are the mechanism by which a particular type of DID and itsassociated DID document are created, resolved, updated, and deactivatedusing a particular verifiable data registry. DID methods are definedusing separate DID method specifications. In the example embodiments,DIDs, VCs, VPs, and the like, may be stored on a blockchain ledger whichincludes the verifiable data registry.

An owner of a DID can be issued a VC establishing some property of theowner by a credential provider (e.g., DMV issuing a driver's license,University issuing a grade transcript, etc.) In the example embodiments,a verifiable credential may establish a property of a blockchain entitythat holds the credential, for example, that the blockchain entity is anendorsing peer, that the blockchain entity is authorized to transact ona particular ledger, that the blockchain entity is authorized toexecute/invoke a particular chaincode, etc. The binding is made secureand tamper-proof using digital signatures which may be recorded withinthe VC. Overall, DIDs have longer lifetimes than VCs (which haveexpiration times). Any network component such as a blockchain peer,orderer, endorser, client, etc. gets a DID at the beginning ofoperation. Subsequently, the participant can request for and obtain VCsfrom credentialing authorities that comprise the SSI network. Each VCcan serve a different (and limited) purpose, like signing a transactionfor inclusion in a block, or signing an asset state that is traded witha different network. How a VC may be used (using a VP, or verifiablepresentation) may depend on policy; e.g., transaction commitment policyrequires a signing peer to prove its membership in an organization thatis part of a network.

Verifiable credentials and verifiable presentations may be serializablein one or more machine-readable data formats, for example, a commaseparated value (CSV) file, an extensible markup language (XML) file, aJavaScript Object Notation (JSON) file, and the like. The process ofserialization and/or de-serialization may be deterministic,bi-directional, and lossless. Any serialization of a verifiablecredential or verifiable presentation may be transformable to thegeneric data model in a deterministic process such that the resultingverifiable credential can be processed in an interoperable fashion. Theserialized form may also be able to be generated from the data modelwithout loss of data or content. Furthermore, verifiable presentations(VPs) can either disclose the attributes of a verifiable credential, orsatisfy derived predicates requested by a verifier. Derived predicatesare Boolean conditions, such as greater than, less than, equal to, is inset, and so on.

In the example embodiments, a DID may be guaranteed to be unique onlywithin the domain of a DID provider (or more typically, a registry), notglobally. If a permissioned network, or group of permissioned networks,decide to trust a single DID registry, then a peer within that setupwill have a unique DID. Otherwise, peers' DIDs can be globally resolveduniquely by the tuple <DID Registry, DID>.

In the example embodiments, a BDD is a verifiable credential of theblockchain network itself based on the individual DIDs of itsparticipants. For validation and authentication of the BDD, a verifierthat receives the BDD can also retrieve network information (DIDs, etc.)of any blockchain peer it desires to verify from a sentinel agentrunning in the blockchain network. The verifier may compare the DIDreceived from the sentinel to the DIDs stored in the BDD to ensure thatthe blockchain peer is among the DIDs stored in the list. In addition,the verifier may also verify the existence of a signature of theblockchain peer included in the proof section of the BDD therebyensuring proof of membership.

FIG. 1A illustrates a cross-network communication environment thatincludes multiple blockchain networks 101 and 102 according to exampleembodiments. Referring to FIG. 1A, blockchain network 101 includes aplurality of blockchain peers 112 and 113 which manage a blockchainledger 105. The blockchain network 101 also includes discovery serviceendpoints 111 and 114 that can discover identity information ofblockchain participants in the blockchain network 101. The discoveryservice endpoints 111 and 114 may be an organizations DID serviceendpoint and can be capable of fetching a BDD from a BDD registry 142.In addition, the blockchain network 101 also includes a membershipservice providers (MSPs) 121 and 122 which may abstract awaycryptographic mechanisms and protocols behind issuing certificates,validating certificates, and user authentication. The MSPs 121 and 122may define identity and rules by which the identities are governedwithin the blockchain network 101 such as authentication, signaturegeneration, and the like. Although not shown in FIG. 1A, the blockchainnetwork 101 may also include an ordering service, a certificateauthority (CA), an admin, and the like.

According to various embodiments, the blockchain network 101 alsoincludes sentinel agents 131 and 132. The sentinels 131 and 132 may bethe endpoints of the blockchain network 101 that are queried/probed byother networks (e.g., any of the entities in blockchain network 102,etc.) The sentinels 131 and 132 may verify the querying entity beforeproviding sensitive membership information to an external blockchainnetwork, and only provide enough information to satisfy the requestwithout divulging additional information. For example, if a peer inanother network requests an identity of the blockchain peer 112, thesentinel 131 may provide only the network information (e.g., DID, VC,etc.) of the blockchain peer 112, without providing any additionalinformation of the other peers and entities in the blockchain network101. The sentinels 131 and 132 may enable secure, consent-based,privacy-preserving, discovery and sync of membership information withother networks.

Various mechanisms exist to ensure simultaneous trustworthiness ofinformation and data privacy. The VC/VP mechanism by its very natureallows the revelation of certain credentials with signatures as proofwhile hiding other attributes one does not wish to claim in a givenscenario. In the example embodiments, a sentinel 131 or 132 may providesome information (e.g., a list of peers/DIDs) while withholding certainother information/metadata about itself, thereby preserving privacy ofthe blockchain network when queried by an external network. In anotherexample, the sentinels 131 and 132 may supply data with Zero-KnowledgeProofs (ZKPs) to reveal only certain attributes about the network in theBDD. The verification process would now include additionalZKP-verification steps through the sentinels 131 and 132. Here, thesentinels 131 and 132 ensure the privacy of sensitive information(including network membership info) while revealing them only whenrequested for valid business reasons.

In this example, the blockchain network 102 may include the sameentities as the blockchain network 101 such as blockchain peers 116 and117 which manage their own blockchain ledger 106, discovery serviceendpoints 115 and 118, MSPs 123 and 124, sentinels 133 and 134, and thelike.

The entities in both of the blockchain networks 101 and 102 may receivedecentralized identifiers (DIDs) from the DID registry 141 shown in FIG.1A. The DID registry 141 may store a mapping between a unique identifierof an entity (e.g., the address, public key, URI, etc.) and acorresponding DID of that entity. Each participant that receives a DIDmay have a unique DID with respect to all other participants on allother networks.

According to various embodiments, each blockchain network 101 and 102may generate their own BDD and store the BDD in a BDD registry 142.Here, the BDD may be stored with a name/identifier of the blockchainnetwork, along with the BDD document that includes the claim field, theproof field, and the metadata. When a participant of the blockchainnetwork 101 (e.g., peer 112) desires to query a peer (e.g., peer 116) inthe blockchain network 102, or vice versa, the participant of theblockchain network 101 may request the BDD of the blockchain network 102from the BDD registry 142. In addition, the participant of theblockchain network 101 may request membership information (e.g., DIDs,etc.) of any of the participants (e.g., peer 116, etc.) of theblockchain network 102 from one of the sentinels 133 and 134. Theparticipant of the blockchain network 101 may compare the data from thesentinels 133 or 134 with the BDD to ensure that the peer 116 is amember of the blockchain network and has validly signed the BDD, priorto performing a cross-network communication.

Furthermore, the BDD may be updated at any time based on the alterationclause stored in the BDD. For example, a new peer or other entity may beadded to the network structure and their signature added to the prooffield of the BDD. Likewise, an existing peer may be removed from thenetwork structure and their signature removed from the proof field.Permissioned blockchain networks are typically formed and maintainedthrough dynamically changing agreements among its members.Interoperation requires the ability for external parties to securelyidentify the network and know its current membership. The BDD describedherein enables a blockchain network to create and maintain a uniqueidentity over time and membership changes. Furthermore, because eachparticipant may provide a signature over the claim which is then storedin the proof section thus ensuring a decentralized management of theBDD. The trusted sentinel enables secure, consent-based,privacy-preserving, discovery and sync of other networks' descriptors.

FIG. 1B illustrates an example of a blockchain declarative descriptor(BDD) 150 according to example embodiments. Each of the blockchainnetworks 101 and 102 may generate their own BDD 150 based on respectivenetwork participants. The BDD 150 may be created by any entity withauthority to sign on behalf of a blockchain network such as a MSP, a CA,a blockchain peer/smart contract, or the like.

Referring to FIG. 1B, the BDD 150 may include a machine-readable file,code, document, etc., in digital format that includes credentialmetadata 160, one or more claims 170, and one or more proofs 180 (e.g.,signatures) associated with the one or more claims 170. The BDD 150 mayinclude information related to the issuing authority (e.g., CA, MSP,etc.), information about a type of credential, information aboutspecific attributes of the credential, information related to how thecredential was derived, information related to constraints on thecredential (terms of use, expiration, etc.). The BDD 150 can representthe same information as a physical credential, except that it is inmachine-readable format (e.g., JSON, XML, CSV, etc.) rather thanhuman-readable form.

The credential metadata 160 may include data that describes propertiesof the BDD 150, for example, the issuer, a schema of the verifiablecredential (e.g., JSON, XML, CSV, etc.) the expiry date/time, an imageof the credential, an identifier of a public key to be used forverification, a revocation mechanism, and the like.

According to various embodiments, the claim field 170 may include anetwork structure 172 which may include a name of the blockchain networkand a list of identifiers of blockchain peers/organizations that areincluded in the blockchain network associated with the BDD. In someembodiments, the identifiers may include DIDs of the participants, or itmay include other information. The network structure 172 may alsoinclude an identification of the roles and responsibilities of each ofthe blockchain peers in the network. For example, the network structure172 may identify the endorsing peers, etc. The claim field 170 may alsoinclude a chaincode field 174 which identifies any chaincodes that areinstalled and executed by the blockchain peers of the blockchainnetwork, along with identifiers of the blockchain peers that run thechaincode. The claim field 170 may also include an alterations clause176 which identifies how a new entity of the blockchain network can beadded to the BDD 150 or an existing entity can be removed from the BDD150/blockchain network. For example, the alteration clause 176 mayspecify a subset of blockchain peers within the blockchain network whichmust agree/endorse the new peer. Here, a consensus of the endorsingpeers (e.g., a quorum, etc.) may be enough to add the new peer.

The proof field 180 may include multi-signature data 182 such as (VCs)of the participants of the blockchain network which have signed over theclaims 170. For example, each and every blockchain peer that is aparticipant of the blockchain network may add a signature (VC) to theproof field 180. As another example, only a predefined peer or subset ofpeers may add a VC to the proof field 180.

The multi-signature data 182 is a collective assent over the claims 170made about a blockchain network structure by all organizationsparticipating in the blockchain network. The proof field 180 may includeas proof of asset a verifiable signature on the network structure 172and the network alteration clause 176, and optionally other claims. Twocollection process examples are: (i) a multi-signature scheme wherebycounter signatures over the network structure 172 are collected within asingle VC. Another example is (ii) an aggregation scheme wherebymultiple VCs, each containing the network structure 172 but only asingle digital signature (by a given organization) are collected into asingle artifact that represents the multi-signature data 180. Either ofthese processes can be implemented using what is referred to as a flowmechanism whereby one participant creates and signs an artifact and thenpasses it to another participant for its signature. The signed (orcounter-signed) artifacts flow through the set of participants until allrequired signatures (or in this case, VCs) are collected.

Furthermore, the creation of the BDD 150 is also open to variousimplementations. One approach is to have a system smart contract (e.g.,a smart contract deployed on every network peer) that manages thiscoordination and collection. The smart contract is executed whenever theblockchain network membership changes and can be triggered by arepresentative of any participating organization. The network structurecontaining the current membership information of the blockchain networkmay be determined and then agreed upon using consensus, along with thenew BDD updation clause. These form the claim of VCs that are issued byeach participant and submitted to the smart contract. The set oftransactions with signatures (called endorsements in Hyperledger Fabric)are collected to form the BDD.

Another example includes a higher layer system application that collectssignatures from blockchain network participants off-chain to produceeither a multi-signature VC or an aggregation of VCs. Other approachescould involve modifying peers or identity providers (like MSPs inHyperledger Fabric) to engineer the collection of VCs to form BDDs. TheBDD 150 may or may not be stored on a blockchain. If the productionmechanism is a smart contract, it will get recorded on-chain as aby-product of the consensus protocol. The BDD's value lies outside thenetwork and is shared with others, stored by each organization (inwhatever store an organizational representative uses). It is, however,typically stored in a global BDD Name Registry for discovery orreference.

Referring again to FIG. 1A, the BDD 150 may be stored in the BDDRegistry 142, which may be an extension (or extrapolation) of aconventional DID registry 141 that maintains decentralized identityrecords as well as credential verification information. In someembodiments, the BDD registry 142 (and the DID registry 141) may be ablockchain (shared ledger) network but it does not have to be. Asanother example, BDDs can also be shared ad hoc by the participant ofone network with a participant of another. Here, the sharer may havestored the BDD in its own local store. The receiver can independentlyvalidate the BDD by cryptographically validating all the VC signatureswithin it, and also use standard processes to validate DIDs of theorganizations that issue individual VCs. The BDD registry 142 may map aname of the blockchain network to its corresponding BDD. Thus, while theBDD may change over time, the network name does not. Thus, the mappingstays the same.

The BDD described herein enables blockchain networks to be mutuallyinteroperable. The interoperability may manifest itself in the form ofdata and asset transfers across networks with communication occurring ina peer-to-peer manner (e.g., peer in a first blockchain network and apeer in a second blockchain network). Though protocols for suchinteroperation exist, they require additional mechanisms to discover,identify, and authenticate networks and their participants. The exampleembodiments overcome this drawback using a BDD which provides a singlecredential that can be used to verify any organization/peer of ablockchain network.

As an example, blockchain network A may have heard of a blockchainnetwork B and wishes to communicate/fetch some data from blockchainnetwork B in a trusted manner (involving data and signatures as proof).In this example, an entity in blockchain network A would query the BDDRegistry for the BDD of blockchain network B, or otherwise obtainblockchain network B's BDD and then validate it. Once it is validated,the entity in network A can now freely communicate with an entity innetwork B in some interoperation protocol as it knows who a participantof B is and who is not. Thus, both blockchain networks A and B may beinteroperating. However, this interoperation depends on both networksbeing always aware of the current network structure, which changes withtime (participants join and leave). They both can track each other'sBDDs and keep this information up-to-date.

FIG. 2A illustrates a blockchain architecture configuration 200,according to example embodiments. Referring to FIG. 2A, the blockchainarchitecture 200 may include certain blockchain elements, for example, agroup of blockchain nodes 202. The blockchain nodes 202 may include oneor more nodes 204-210 (these four nodes are depicted by example only).These nodes participate in a number of activities, such as blockchaintransaction addition and validation process (consensus). One or more ofthe blockchain nodes 204-210 may endorse transactions based onendorsement policy and may provide an ordering service for allblockchain nodes in the architecture 200. A blockchain node may initiatea blockchain authentication and seek to write to a blockchain immutableledger stored in blockchain layer 216, a copy of which may also bestored on the underpinning physical infrastructure 214. The blockchainconfiguration may include one or more applications 224 which are linkedto application programming interfaces (APIs) 222 to access and executestored program/application code 220 (e.g., chaincode, smart contracts,etc.) which can be created according to a customized configurationsought by participants and can maintain their own state, control theirown assets, and receive external information. This can be deployed as atransaction and installed, via appending to the distributed ledger, onall blockchain nodes 204-210.

The blockchain base or platform 212 may include various layers ofblockchain data, services (e.g., cryptographic trust services, virtualexecution environment, etc.), and underpinning physical computerinfrastructure that may be used to receive and store new transactionsand provide access to auditors which are seeking to access data entries.The blockchain layer 216 may expose an interface that provides access tothe virtual execution environment necessary to process the program codeand engage the physical infrastructure 214. Cryptographic trust services218 may be used to verify transactions such as asset exchangetransactions and keep information private.

The blockchain architecture configuration of FIG. 2A may process andexecute program/application code 220 via one or more interfaces exposed,and services provided, by blockchain platform 212. The code 220 maycontrol blockchain assets. For example, the code 220 can store andtransfer data, and may be executed by nodes 204-210 in the form of asmart contract and associated chaincode with conditions or other codeelements subject to its execution. As a non-limiting example, smartcontracts may be created to execute reminders, updates, and/or othernotifications subject to the changes, updates, etc. The smart contractscan themselves be used to identify rules associated with authorizationand access requirements and usage of the ledger. For example, the smartcontract (or chaincode executing the logic of the smart contract) mayread blockchain data 226 which may be processed by one or moreprocessing entities (e.g., virtual machines) included in the blockchainlayer 216 to generate results 228 including alerts, determiningliability, and the like, within a complex service scenario. The physicalinfrastructure 214 may be utilized to retrieve any of the data orinformation described herein.

A smart contract may be created via a high-level application andprogramming language, and then written to a block in the blockchain. Thesmart contract may include executable code which is registered, stored,and/or replicated with a blockchain (e.g., distributed network ofblockchain peers). A transaction is an execution of the smart contractlogic which can be performed in response to conditions associated withthe smart contract being satisfied. The executing of the smart contractmay trigger a trusted modification(s) to a state of a digital blockchainledger. The modification(s) to the blockchain ledger caused by the smartcontract execution may be automatically replicated throughout thedistributed network of blockchain peers through one or more consensusprotocols.

The smart contract may write data to the blockchain in the format ofkey-value pairs. Furthermore, the smart contract code can read thevalues stored in a blockchain and use them in application operations.The smart contract code can write the output of various logic operationsinto one or more blocks within the blockchain. The code may be used tocreate a temporary data structure in a virtual machine or othercomputing platform. Data written to the blockchain can be public and/orcan be encrypted and maintained as private. The temporary data that isused/generated by the smart contract is held in memory by the suppliedexecution environment, then deleted once the data needed for theblockchain is identified.

A chaincode may include the code interpretation (e.g., the logic) of asmart contract. For example, the chaincode may include a packaged anddeployable version of the logic within the smart contract. As describedherein, the chaincode may be program code deployed on a computingnetwork, where it is executed and validated by chain validators togetherduring a consensus process. The chaincode may receive a hash andretrieve from the blockchain a hash associated with the data templatecreated by use of a previously stored feature extractor. If the hashesof the hash identifier and the hash created from the stored identifiertemplate data match, then the chaincode sends an authorization key tothe requested service. The chaincode may write to the blockchain dataassociated with the cryptographic details.

FIG. 2B illustrates an example of a blockchain transactional flow 250between nodes of the blockchain in accordance with an exampleembodiment. Referring to FIG. 2B, the transaction flow may include aclient node 260 transmitting a transaction proposal 291 to an endorsingpeer node 281. The endorsing peer 281 may verify the client signatureand execute a chaincode function to initiate the transaction. The outputmay include the chaincode results, a set of key/value versions that wereread in the chaincode (read set), and the set of keys/values that werewritten in chaincode (write set). Here, the endorsing peer 281 maydetermine whether or not to endorse the transaction proposal. Theproposal response 292 is sent back to the client 260 along with anendorsement signature, if approved. The client 260 assembles theendorsements into a transaction payload 293 and broadcasts it to anordering service node 284. The ordering service node 284 then deliversordered transactions as blocks to all peers 281-283 on a channel. Beforecommittal to the blockchain, each peer 281-283 may validate thetransaction. For example, the peers may check the endorsement policy toensure that the correct allotment of the specified peers have signed theresults and authenticated the signatures against the transaction payload293.

Referring again to FIG. 2B, the client node initiates the transaction291 by constructing and sending a request to the peer node 281, which isan endorser. The client 260 may include an application leveraging asupported software development kit (SDK), which utilizes an availableAPI to generate a transaction proposal. The proposal is a request toinvoke a chaincode function so that data can be read and/or written tothe ledger (i.e., write new key value pairs for the assets). The SDK mayserve as a shim to package the transaction proposal into a properlyarchitected format (e.g., protocol buffer over a remote procedure call(RPC)) and take the client's cryptographic credentials to produce aunique signature for the transaction proposal.

In response, the endorsing peer node 281 may verify (a) that thetransaction proposal is well formed, (b) the transaction has not beensubmitted already in the past (replay-attack protection), (c) thesignature is valid, and (d) that the submitter (client 260, in theexample) is properly authorized to perform the proposed operation onthat channel. The endorsing peer node 281 may take the transactionproposal inputs as arguments to the invoked chaincode function. Thechaincode is then executed against a current state database to producetransaction results including a response value, read set, and write set.However, no updates are made to the ledger at this point. In 292, theset of values, along with the endorsing peer node's 281 signature ispassed back as a proposal response 292 to the SDK of the client 260which parses the payload for the application to consume.

In response, the application of the client 260 inspects/verifies thesignatures of the endorsing peers and compares the proposal responses todetermine if the proposal response is the same. If the chaincode onlyqueried the ledger, the application would inspect the query response andwould typically not submit the transaction to the ordering node service284. If the client application intends to submit the transaction to theordering node service 284 to update the ledger, the applicationdetermines if the specified endorsement policy has been fulfilled beforesubmitting (i.e., did all peer nodes necessary for the transactionendorse the transaction). Here, the client may include only one ofmultiple parties to the transaction. In this case, each client may havetheir own endorsing node, and each endorsing node will need to endorsethe transaction. The architecture is such that even if an applicationselects not to inspect responses or otherwise forwards an unendorsedtransaction, the endorsement policy will still be enforced by peers andupheld at the commit validation phase.

After successful inspection, in step 293 the client 260 assemblesendorsements into a transaction proposal and broadcasts the transactionproposal and response within a transaction message to the ordering node284. The transaction may contain the read/write sets, the endorsing peersignatures and a channel ID. The ordering node 284 does not need toinspect the entire content of a transaction in order to perform itsoperation, instead the ordering node 284 may simply receive transactionsfrom all channels in the network, order them chronologically by channel,and create blocks of transactions per channel.

The blocks are delivered from the ordering node 284 to all peer nodes281-283 on the channel. The data section within the block may bevalidated to ensure an endorsement policy is fulfilled and to ensurethat there have been no changes to ledger state for read set variablessince the read set was generated by the transaction execution.Furthermore, in step 295 each peer node 281-283 appends the block to thechannel's chain, and for each valid transaction the write sets arecommitted to current state database. An event may be emitted, to notifythe client application that the transaction (invocation) has beenimmutably appended to the chain, as well as to notify whether thetransaction was validated or invalidated.

In the example of FIG. 2B, the client node 260 and each of theblockchain peers 281-284 may use a verifiable credential as a signature.As the transaction moves through the different steps of FIG. 2B, each ofthe client node 260 and the blockchain peers 281-284 may attach theirrespective VC to a step that they have performed. In this example, eachof the blockchain peers 281-284 may include a set of VCs (e.g., one ormore VCs) that provide identity and membership information associatedwith the blockchain peers 281-284. For example, the client node 260 mayinclude a verifiable certificate with a claim issued by a MSP of theblockchain network that identifies the client as a member fortransacting on the blockchain. As another example, the blockchain peers281-283 may include VCs that identify the blockchain peers 281-283 asendorsing peers of the blockchain. Meanwhile, the blockchain peer 284may include a VC that identifies the blockchain peer 284 as an orderingnode of the blockchain. Many other VCs are possible. For example,particular channels on the blockchain (e.g., different blockchains onthe same ledger) may require different VCs in order to serve as aclient, a peer, an endorser, and orderer, and the like. As anotherexample, different types of transactions and/or chaincodes may require aseparate VC by the clients, the peers, etc. For example, a client mayonly submit a transaction to invoke a particular chaincode if the clienthas a VC identifying the client has authority to use such chaincode.

FIG. 3A illustrates an example of a permissioned blockchain network 300,which features a distributed, decentralized peer-to-peer architecture.In this example, a blockchain user 302 may initiate a transaction to thepermissioned blockchain 304. In this example, the transaction can be adeploy, invoke, or query, and may be issued through a client-sideapplication leveraging an SDK, directly through an API, etc. Networksmay provide access to a regulator 306, such as an auditor. A blockchainnetwork operator 308 manages member permissions, such as enrolling theregulator 306 as an “auditor” and the blockchain user 302 as a “client”.An auditor could be restricted only to querying the ledger whereas aclient could be authorized to deploy, invoke, and query certain types ofchaincode.

A blockchain developer 310 can write chaincode and client-sideapplications. The blockchain developer 310 can deploy chaincode directlyto the network through an interface. To include credentials from atraditional data source 312 in chaincode, the developer 310 could use anout-of-band connection to access the data. In this example, theblockchain user 302 connects to the permissioned blockchain 304 througha peer node 314. Before proceeding with any transactions, the peer node314 retrieves the user's enrollment and transaction certificates from acertificate authority 316, which manages user roles and permissions. Insome cases, blockchain users must possess these digital certificates inorder to transact on the permissioned blockchain 304. Meanwhile, a userattempting to utilize chaincode may be required to verify theircredentials on the traditional data source 312. To confirm the user'sauthorization, chaincode can use an out-of-band connection to this datathrough a traditional processing platform 318.

FIG. 3B illustrates another example of a permissioned blockchain network320, which features a distributed, decentralized peer-to-peerarchitecture. In this example, a blockchain user 322 may submit atransaction to the permissioned blockchain 324. In this example, thetransaction can be a deploy, invoke, or query, and may be issued througha client-side application leveraging an SDK, directly through an API,etc. Networks may provide access to a regulator 326, such as an auditor.A blockchain network operator 328 manages member permissions, such asenrolling the regulator 326 as an “auditor” and the blockchain user 322as a “client”. An auditor could be restricted only to querying theledger whereas a client could be authorized to deploy, invoke, and querycertain types of chaincode.

A blockchain developer 330 writes chaincode and client-sideapplications. The blockchain developer 330 can deploy chaincode directlyto the network through an interface. To include credentials from atraditional data source 332 in chaincode, the developer 330 could use anout-of-band connection to access the data. In this example, theblockchain user 322 connects to the network through a peer node 334.Before proceeding with any transactions, the peer node 334 retrieves theuser's enrollment and transaction certificates from the certificateauthority 336. In some cases, blockchain users must possess thesedigital certificates in order to transact on the permissioned blockchain324. Meanwhile, a user attempting to utilize chaincode may be requiredto verify their credentials on the traditional data source 332. Toconfirm the user's authorization, chaincode can use an out-of-bandconnection to this data through a traditional processing platform 338.

In some embodiments, the blockchain herein may be a permissionlessblockchain. In contrast with permissioned blockchains which requirepermission to join, anyone can join a permissionless blockchain. Forexample, to join a permissionless blockchain a user may create apersonal address and begin interacting with the network, by submittingtransactions, and hence adding entries to the ledger. Additionally, allparties have the choice of running a node on the system and employingthe mining protocols to help verify transactions.

FIG. 3C illustrates a process 350 of a transaction being processed by apermissionless blockchain 352 including a plurality of nodes 354. Asender 356 desires to send payment or some other form of value (e.g., adeed, medical records, a contract, a good, a service, or any other assetthat can be encapsulated in a digital record) to a recipient 358 via thepermissionless blockchain 352. In one embodiment, each of the senderdevice 356 and the recipient device 358 may have digital wallets(associated with the blockchain 352) that provide user interfacecontrols and a display of transaction parameters. In response, thetransaction is broadcast throughout the blockchain 352 to the nodes 354.Depending on the blockchain's 352 network parameters the nodes verify360 the transaction based on rules (which may be pre-defined ordynamically allocated) established by the permissionless blockchain 352creators. For example, this may include verifying identities of theparties involved, etc. The transaction may be verified immediately or itmay be placed in a queue with other transactions and the nodes 354determine if the transactions are valid based on a set of network rules.

In structure 362, valid transactions are formed into a block and sealedwith a lock (hash). This process may be performed by mining nodes amongthe nodes 354. Mining nodes may utilize additional software specificallyfor mining and creating blocks for the permissionless blockchain 352.Each block may be identified by a hash (e.g., 256 bit number, etc.)created using an algorithm agreed upon by the network. Each block mayinclude a header, a pointer or reference to a hash of a previous block'sheader in the chain, and a group of valid transactions. The reference tothe previous block's hash is associated with the creation of the secureindependent chain of blocks.

Before blocks can be added to the blockchain, the blocks must bevalidated. Validation for the permissionless blockchain 352 may includea proof-of-work (PoW) which is a solution to a puzzle derived from theblock's header. Although not shown in the example of FIG. 3C, anotherprocess for validating a block is proof-of-stake. Unlike theproof-of-work, where the algorithm rewards miners who solve mathematicalproblems, with the proof of stake, a creator of a new block is chosen ina deterministic way, depending on its wealth, also defined as “stake.”Then, a similar proof is performed by the selected/chosen node.

With mining 364, nodes try to solve the block by making incrementalchanges to one variable until the solution satisfies a network-widetarget. This creates the PoW thereby ensuring correct answers. In otherwords, a potential solution must prove that computing resources weredrained in solving the problem. In some types of permissionlessblockchains, miners may be rewarded with value (e.g., coins, etc.) forcorrectly mining a block.

Here, the PoW process, alongside the chaining of blocks, makesmodifications of the blockchain extremely difficult, as an attacker mustmodify all subsequent blocks in order for the modifications of one blockto be accepted. Furthermore, as new blocks are mined, the difficulty ofmodifying a block increases, and the number of subsequent blocksincreases. With distribution 366, the successfully validated block isdistributed through the permissionless blockchain 352 and all nodes 354add the block to a majority chain which is the permissionlessblockchain's 352 auditable ledger. Furthermore, the value in thetransaction submitted by the sender 356 is deposited or otherwisetransferred to the digital wallet of the recipient device 358.

In the example embodiments, a verifiable Credential (VC) such as BDDextends DID, is tamper-evident, and provides a verifiable set of claimsmade by an issuer. A verifiable presentation (VP) may be derived fromVC(s)—to present specific credential(s) attributes that are shared withspecific verifier. In some embodiments, a VC may contain datasynthetized from the original credential (e.g., zero knowledge proofs,etc.) The network registry may be interacted with by a verifier toobtain information for validating a BDD. For example, the verifier mayprovide the name of the network to the network registry and receive acorresponding BDD in response. The registry mediates the creation andverification of identities, credential schemas, etc. The DIDs of thenetwork participants may also be included in the BDD. DIDs may be usedto identify blockchain network components. In private blockchainnetworks (Fabric, Corda, etc.) clients as well as all active componentsmay have DID identities. In Fabric peers and orderers have DIDidentities.

The network registry can be hosted within an external network, and insome embodiments, may include a blockchain network where the networkregistry is stored on a distributed ledger. The external network canserve as an identity network for multiple networks, serving as a bridge(or mediator) for inter-network exchanges. The external network allowsunified and simplified identity management across organization(s) orlarge ecosystem. This identity mechanism allows for an overall externalnetwork-based configuration management mechanism.

FIG. 4A illustrates a process 400A of generating a BDD based onblockchain organization information according to example embodiments.Referring to FIG. 4A, a BDD is created for a blockchain network 410represented as “blockchain network D”. In this example, the blockchainnetwork 410 includes four blockchain peers 411, 412, 413, and 414, whicheach co-manage a blockchain ledger 416. Furthermore, each of theblockchain peers 411-414 have their own DID assigned thereto. In thisexample, a membership service provider (MSP) 415 of the blockchainnetwork 410 may request the DIDs from the blockchain peers 411-414 andstore the DIDs in a network structure of the claim field of the BDD. TheMSP 415 may also request VCs of the blockchain peers 411-414 (whichinclude signature data), and store the VCs within the proof field of theBDD. Furthermore, the MSP 415 may add metadata about the blockchainnetwork 410 to the metadata field. The resulting BDD D that isbuilt/constructed by the MSP 415 may be transmitted to a BDD registry420 where it is stored as an entry 423 with a network name value 421 anda BDD value 422.

It should also be appreciated that the BDD D may be constructed by anumber of different entities. For example, the BDD D may be constructedby a blockchain peer with a smart contract running therein forcollecting the DIDs and signature data (VCs). As another example, theBDD D may be built by a CA or other trusted entity. In some embodiments,the MSP or the CA may not be dedicated to the particular network.

FIG. 4B illustrates a process 400B of verifying a BDD and performing aninter-network communication according to example embodiments. Referringto FIG. 4B, a blockchain peer 431 that manages a blockchain ledger 432in blockchain network 430 (blockchain network E), desires to communicatewith blockchain peer 411 in blockchain network 410 (blockchain networkD). To verify that the blockchain peer 411 is a valid member of theblockchain network 410, the blockchain peer 431 may query the BDDregistry 420 for the BDD 422. For example, the blockchain peer 431 maytransmit a network name (network D) of the blockchain network 410 to theBDD registry 420. In response, the BDD registry 420 may identify thecorresponding BDD 422 mapped to the network name 421 in an entry 423 ofthe BDD registry 420, and provide the BDD 422 to the blockchain peer 431in the blockchain network 430.

The blockchain peer 431 may also query the blockchain network 410 forinformation about the blockchain peer 411. In this case, the blockchainpeer 431 may query a sentinel 417 which is a dedicated endpoint forproviding network information about the blockchain network 410. Here,the sentinel 417 may provide some information about the blockchainnetwork 410, such as the DID of the blockchain peer 411, or a list ofDIDs of all blockchain peers of the blockchain network 410, withoutproviding any other network information such as the network structure,chaincode, etc.

In response to receiving both the BDD 422 from the BDD registry 420 andthe network information from the sentinel 417, the blockchain peer 431may verify that the DID of the blockchain peer 411 received from thesentinel 417 is included in the list of DIDs in the network structure ofthe BDD 422. The blockchain peer 431 may also verify that a VC of theblockchain peer 411 is included in the proof section of the BDD 422.Upon confirming these attributes, the blockchain peer 431 may perform aninter-network communication with blockchain peer 411 such as messaging,transacting, and the like.

FIG. 5A illustrates a method 510 of generating a blockchain declarativedescriptor according to example embodiments. As a non-limiting example,the method 510 may be performed by an entity in a blockchain networksuch as a blockchain peer (smart contract), a MSP, a CA, a combinationof entities, and the like. Referring to FIG. 5A, in 511, the method mayinclude retrieving decentralized identifiers (DIDs) of a plurality ofblockchain peers included within a blockchain network. For example, theDIDs may be assigned by an SSI network or other DID-based entity. EachDID may uniquely represent a different network component (e.g., peer,orderer, client, etc.) of the blockchain network.

In 512, the method may include generating a blockchain declarativedescriptor (BDD) which uniquely identifies the blockchain network, wherethe BDD comprises a machine-readable data file with a first fieldincludes the retrieved DIDs of the blockchain network, a second fieldincluding signatures of the plurality of blockchain peers, and a thirdfield including metadata. The signatures may include verifiablecredentials (VCs) that have been generated for the plurality ofblockchain peers based on their respective DIDs. In 513, the method mayinclude transmitting the generated BDD to a blockchain network registrywhere the BDD can be stored and accessible to other blockchain networks.

In some embodiments, the method may further include receiving a documentthat has been signed by each of the plurality of blockchain peers of theblockchain network, and storing the document within the second field ofthe BDD. In some embodiments, the method may include receiving aplurality of signed documents from the plurality of blockchain peers,respectively, where each document is signed by a different blockchainpeer, and storing the plurality of documents within the second field ofthe BDD. In some embodiments, the method may include storing ablockchain network updation descriptor within the first field of the BDDincluding the network structure. In some embodiments, the method mayfurther include receiving via a sentinel installed in the blockchainnetwork, a request for the BDD of the blockchain network from ablockchain peer of a second network.

In some embodiments, the method may further include transmitting via thesentinel installed in the blockchain network, the DIDs of the pluralityof blockchain peers included in the first field of the BDD without themetadata in the third field of the BDD. In some embodiments, the methodmay further include detecting a new blockchain peer within theblockchain network, and updating the first field of the BDD to includethe DID of the new blockchain peer and the second field to include asignature of the new blockchain peer. In some embodiments, the methodmay further include identifying a chaincode installed within theblockchain network, and storing a name of the chaincode within the firstfield of the BDD.

FIG. 5B illustrates a method 520 of verifying a BDD and performing aninter-network communication according to example embodiments. Forexample, the method 520 may be performed by an entity in a blockchainnetwork such as a blockchain peer, a client, an ordering node, and thelike. Referring to FIG. 5B, in 521, the method may include querying anetwork registry for a blockchain declarative descriptor (BDD) of afirst blockchain network, the BDD including a network structure andidentifiers of a plurality of peers of the first blockchain network. In522, the method may include retrieving a decentralized identifiers (DID)from the first blockchain network. Here, the DIDs may uniquely representan entity of the first blockchain network such as a blockchain peer, andthe like.

In 523, the method may include verifying the DID of the entity based onthe BDD of the first blockchain network. For example, the verifying mayinclude comparing the retrieved DID to the DIDs included in the BDD toverify that the DID exists in the BDD. In 524, the method may includeverifying that a signature (e.g., a verifiable credential, etc.) of theentity exists in the proof field of the BDD. In response to successfulverifications in 523 and 425, in 525, the method may includetransmitting an inter-network communication from a peer in firstblockchain network to a peer in second blockchain network.

In some embodiments, the retrieving may include probing a sentinelinstalled within the first blockchain network for the DIDs. In someembodiments, the network registry may include a database of entries,where each entry includes a name of a blockchain network paired with arespective BDD of the blockchain network. In some embodiments, the BDDmay include a machine-readable data file with a first field includingthe network structure, a second field including signatures of theplurality of peers, and a third field including metadata.

FIG. 6A illustrates an example system 600 that includes a physicalinfrastructure 610 configured to perform various operations according toexample embodiments. Referring to FIG. 6A, the physical infrastructure610 includes a module 612 and a module 614. The module 614 includes ablockchain 620 and a smart contract 630 (which may reside on theblockchain 620), that may execute any of the operational steps 608 (inmodule 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6B illustrates another example system 640 configured to performvarious operations according to example embodiments. Referring to FIG.6B, the system 640 includes a module 612 and a module 614. The module614 includes a blockchain 620 and a smart contract 630 (which may resideon the blockchain 620), that may execute any of the operational steps608 (in module 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6C illustrates an example system configured to utilize a smartcontract configuration among contracting parties and a mediating serverconfigured to enforce the smart contract terms on the blockchainaccording to example embodiments. Referring to FIG. 6C, theconfiguration 650 may represent a communication session, an assettransfer session or a process or procedure that is driven by a smartcontract 630 which explicitly identifies one or more user devices 652and/or 656. The execution, operations and results of the smart contractexecution may be managed by a server 654. Content of the smart contract630 may require digital signatures by one or more of the entities 652and 656 which are parties to the smart contract transaction. The resultsof the smart contract execution may be written to a blockchain 620 as ablockchain transaction. The smart contract 630 resides on the blockchain620 which may reside on one or more computers, servers, processors,memories, and/or wireless communication devices.

FIG. 6D illustrates a system 660 including a blockchain, according toexample embodiments. Referring to the example of FIG. 6D, an applicationprogramming interface (API) gateway 662 provides a common interface foraccessing blockchain logic (e.g., smart contract 630 or other chaincode)and data (e.g., distributed ledger, etc.). In this example, the APIgateway 662 is a common interface for performing transactions (invoke,queries, etc.) on the blockchain by connecting one or more entities 652and 656 to a blockchain peer (i.e., server 654). Here, the server 654 isa blockchain network peer component that holds a copy of the world stateand a distributed ledger allowing clients 652 and 656 to query data onthe world state as well as submit transactions into the blockchainnetwork where, depending on the smart contract 630 and endorsementpolicy, endorsing peers will run the smart contracts 630.

The above embodiments may be implemented in hardware, in a computerprogram executed by a processor, in firmware, or in a combination of theabove. A computer program may be embodied on a computer readable medium,such as a storage medium. For example, a computer program may reside inrandom access memory (“RAM”), flash memory, read-only memory (“ROM”),erasable programmable read-only memory (“EPROM”), electrically erasableprogrammable read-only memory (“EEPROM”), registers, hard disk, aremovable disk, a compact disk read-only memory (“CD-ROM”), or any otherform of storage medium known in the art.

An exemplary storage medium may be coupled to the processor such thatthe processor may read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anapplication specific integrated circuit (“ASIC”). In the alternative,the processor and the storage medium may reside as discrete components.

FIG. 7A illustrates a process 700 of a new block being added to adistributed ledger 720, according to example embodiments, and FIG. 7Billustrates contents of a new data block structure 730 for blockchain,according to example embodiments. Referring to FIG. 7A, clients (notshown) may submit transactions to blockchain nodes 711, 712, and/or 713.Clients may be instructions received from any source to enact activityon the blockchain 720. As an example, clients may be applications thatact on behalf of a requester, such as a device, person or entity topropose transactions for the blockchain. The plurality of blockchainpeers (e.g., blockchain nodes 711, 712, and 713) may maintain a state ofthe blockchain network and a copy of the distributed ledger 720.Different types of blockchain nodes/peers may be present in theblockchain network including endorsing peers which simulate and endorsetransactions proposed by clients and committing peers which verifyendorsements, validate transactions, and commit transactions to thedistributed ledger 720. In this example, the blockchain nodes 711, 712,and 713 may perform the role of endorser node, committer node, or both.

The distributed ledger 720 includes a blockchain which stores immutable,sequenced records in blocks, and a state database 724 (current worldstate) maintaining a current state of the blockchain 722. Onedistributed ledger 720 may exist per channel and each peer maintains itsown copy of the distributed ledger 720 for each channel of which theyare a member. The blockchain 722 is a transaction log, structured ashash-linked blocks where each block contains a sequence of Ntransactions. Blocks may include various components such as shown inFIG. 7B. The linking of the blocks (shown by arrows in FIG. 7A) may begenerated by adding a hash of a prior block's header within a blockheader of a current block. In this way, all transactions on theblockchain 722 are sequenced and cryptographically linked togetherpreventing tampering with blockchain data without breaking the hashlinks. Furthermore, because of the links, the latest block in theblockchain 722 represents every transaction that has come before it. Theblockchain 722 may be stored on a peer file system (local or attachedstorage), which supports an append-only blockchain workload.

The current state of the blockchain 722 and the distributed ledger 722may be stored in the state database 724. Here, the current state datarepresents the latest values for all keys ever included in the chaintransaction log of the blockchain 722. Chaincode invocations executetransactions against the current state in the state database 724. Tomake these chaincode interactions extremely efficient, the latest valuesof all keys are stored in the state database 724. The state database 724may include an indexed view into the transaction log of the blockchain722, it can therefore be regenerated from the chain at any time. Thestate database 724 may automatically get recovered (or generated ifneeded) upon peer startup, before transactions are accepted.

Endorsing nodes receive transactions from clients and endorse thetransaction based on simulated results. Endorsing nodes hold smartcontracts which simulate the transaction proposals. When an endorsingnode endorses a transaction, the endorsing nodes creates a transactionendorsement which is a signed response from the endorsing node to theclient application indicating the endorsement of the simulatedtransaction. The method of endorsing a transaction depends on anendorsement policy which may be specified within chaincode. An exampleof an endorsement policy is “the majority of endorsing peers mustendorse the transaction”. Different channels may have differentendorsement policies. Endorsed transactions are forward by the clientapplication to ordering service 710.

The ordering service 710 accepts endorsed transactions, orders them intoa block, and delivers the blocks to the committing peers. For example,the ordering service 710 may initiate a new block when a threshold oftransactions has been reached, a timer times out, or another condition.In the example of FIG. 7A, blockchain node 712 is a committing peer thathas received a new data new data block 730 for storage on blockchain720. The first block in the blockchain may be referred to as a genesisblock which includes information about the blockchain, its members, thedata stored therein, etc.

The ordering service 710 may be made up of a cluster of orderers. Theordering service 710 does not process transactions, smart contracts, ormaintain the shared ledger. Rather, the ordering service 710 may acceptthe endorsed transactions and specifies the order in which thosetransactions are committed to the distributed ledger 720. Thearchitecture of the blockchain network may be designed such that thespecific implementation of ‘ordering’ (e.g., Solo, Kafka, BFT, etc.)becomes a pluggable component.

Transactions are written to the distributed ledger 720 in a consistentorder. The order of transactions is established to ensure that theupdates to the state database 724 are valid when they are committed tothe network. Unlike a cryptocurrency blockchain system (e.g., Bitcoin,etc.) where ordering occurs through the solving of a cryptographicpuzzle, or mining, in this example the parties of the distributed ledger720 may choose the ordering mechanism that best suits that network.

When the ordering service 710 initializes a new data block 730, the newdata block 730 may be broadcast to committing peers (e.g., blockchainnodes 711, 712, and 713). In response, each committing peer validatesthe transaction within the new data block 730 by checking to make surethat the read set and the write set still match the current world statein the state database 724. Specifically, the committing peer candetermine whether the read data that existed when the endorserssimulated the transaction is identical to the current world state in thestate database 724. When the committing peer validates the transaction,the transaction is written to the blockchain 722 on the distributedledger 720, and the state database 724 is updated with the write datafrom the read-write set. If a transaction fails, that is, if thecommitting peer finds that the read-write set does not match the currentworld state in the state database 724, the transaction ordered into ablock will still be included in that block, but it will be marked asinvalid, and the state database 724 will not be updated.

Referring to FIG. 7B, a new data block 730 (also referred to as a datablock) that is stored on the blockchain 722 of the distributed ledger720 may include multiple data segments such as a block header 740, blockdata 750 (block data section), and block metadata 760. It should beappreciated that the various depicted blocks and their contents, such asnew data block 730 and its contents, shown in FIG. 7B are merelyexamples and are not meant to limit the scope of the exampleembodiments. In a conventional block, the data section may storetransactional information of N transaction(s) (e.g., 1, 10, 100, 500,1000, 2000, 3000, etc.) within the block data 750.

The new data block 730 may include a link to a previous block (e.g., onthe blockchain 722 in FIG. 7A) within the block header 740. Inparticular, the block header 740 may include a hash of a previousblock's header. The block header 740 may also include a unique blocknumber, a hash of the block data 750 of the new data block 730, and thelike. The block number of the new data block 730 may be unique andassigned in various orders, such as an incremental/sequential orderstarting from zero.

The block metadata 760 may store multiple fields of metadata (e.g., as abyte array, etc.). Metadata fields may include signature on blockcreation, a reference to a last configuration block, a transactionfilter identifying valid and invalid transactions within the block, lastoffset persisted of an ordering service that ordered the block, and thelike. The signature, the last configuration block, and the orderermetadata may be added by the ordering service 710. Meanwhile, acommitter of the block (such as blockchain node 712) may addvalidity/invalidity information based on an endorsement policy,verification of read/write sets, and the like. The transaction filtermay include a byte array of a size equal to the number of transactionsthat are included in the block data 750 and a validation codeidentifying whether a transaction was valid/invalid.

FIG. 7C illustrates an embodiment of a blockchain 770 for digitalcontent in accordance with the embodiments described herein. The digitalcontent may include one or more files and associated information. Thefiles may include media, images, video, audio, text, links, graphics,animations, web pages, documents, or other forms of digital content. Theimmutable, append-only aspects of the blockchain serve as a safeguard toprotect the integrity, validity, and authenticity of the digitalcontent, making it suitable use in legal proceedings where admissibilityrules apply or other settings where evidence is taken into considerationor where the presentation and use of digital information is otherwise ofinterest. In this case, the digital content may be referred to asdigital evidence.

The blockchain may be formed in various ways. In one embodiment, thedigital content may be included in and accessed from the blockchainitself. For example, each block of the blockchain may store a hash valueof reference information (e.g., header, value, etc.) along theassociated digital content. The hash value and associated digitalcontent may then be encrypted together. Thus, the digital content ofeach block may be accessed by decrypting each block in the blockchain,and the hash value of each block may be used as a basis to reference aprevious block. This may be illustrated as follows:

Block 1 Block 2 . . . Block N Hash Value 1 Hash Value 2 Hash Value NDigital Content 1 Digital Content 2 Digital Content N

In one embodiment, the digital content may be not included in theblockchain. For example, the blockchain may store the encrypted hashesof the content of each block without any of the digital content. Thedigital content may be stored in another storage area or memory addressin association with the hash value of the original file. The otherstorage area may be the same storage device used to store the blockchainor may be a different storage area or even a separate relationaldatabase. The digital content of each block may be referenced oraccessed by obtaining or querying the hash value of a block of interestand then looking up that has value in the storage area, which is storedin correspondence with the actual digital content. This operation may beperformed, for example, a database gatekeeper. This may be illustratedas follows:

Blockchain Storage Area Block 1 Hash Value Block 1 Hash Value . . .Content . . . . . . Block N Hash Value Block N Hash Value . . . Content

In the example embodiment of FIG. 7C, the blockchain 770 includes anumber of blocks 778 ₁, 778 ₂, . . . 778 _(N) cryptographically linkedin an ordered sequence, where N≥1. The encryption used to link theblocks 778 ₁, 778 ₂, . . . 778 _(N) may be any of a number of keyed orun-keyed Hash functions. In one embodiment, the blocks 778 ₁, 778 ₂, . .. 778 _(N) are subject to a hash function which produces n-bitalphanumeric outputs (where n is 256 or another number) from inputs thatare based on information in the blocks. Examples of such a hash functioninclude, but are not limited to, a SHA-type (SHA stands for Secured HashAlgorithm) algorithm, Merkle-Damgard algorithm, HAIFA algorithm,Merkle-tree algorithm, nonce-based algorithm, and anon-collision-resistant PRF algorithm. In another embodiment, the blocks778 ₁, 778 ₂, . . . , 778 _(N) may be cryptographically linked by afunction that is different from a hash function. For purposes ofillustration, the following description is made with reference to a hashfunction, e.g., SHA-2.

Each of the blocks 778 ₁, 778 ₂, . . . , 778 _(N) in the blockchainincludes a header, a version of the file, and a value. The header andthe value are different for each block as a result of hashing in theblockchain. In one embodiment, the value may be included in the header.As described in greater detail below, the version of the file may be theoriginal file or a different version of the original file.

The first block 778 ₁ in the blockchain is referred to as the genesisblock and includes the header 772 ₁, original file 774 ₁, and an initialvalue 776 ₁. The hashing scheme used for the genesis block, and indeedin all subsequent blocks, may vary. For example, all the information inthe first block 778 ₁ may be hashed together and at one time, or each ora portion of the information in the first block 778 ₁ may be separatelyhashed and then a hash of the separately hashed portions may beperformed.

The header 772 ₁ may include one or more initial parameters, which, forexample, may include a version number, timestamp, nonce, rootinformation, difficulty level, consensus protocol, duration, mediaformat, source, descriptive keywords, and/or other informationassociated with original file 774 ₁ and/or the blockchain. The header772 ₁ may be generated automatically (e.g., by blockchain networkmanaging software) or manually by a blockchain participant. Unlike theheader in other blocks 778 ₂ to 778 _(N) in the blockchain, the header772 ₁ in the genesis block does not reference a previous block, simplybecause there is no previous block.

The original file 774 ₁ in the genesis block may be, for example, dataas captured by a device with or without processing prior to itsinclusion in the blockchain. The original file 774 ₁ is received throughthe interface of the system from the device, media source, or node. Theoriginal file 774 ₁ is associated with metadata, which, for example, maybe generated by a user, the device, and/or the system processor, eithermanually or automatically. The metadata may be included in the firstblock 778 ₁ in association with the original file 774 ₁.

The value 776 ₁ in the genesis block is an initial value generated basedon one or more unique attributes of the original file 774 ₁. In oneembodiment, the one or more unique attributes may include the hash valuefor the original file 774 ₁, metadata for the original file 774 ₁, andother information associated with the file. In one implementation, theinitial value 776 ₁ may be based on the following unique attributes:

-   -   1) SHA-2 computed hash value for the original file    -   2) originating device ID    -   3) starting timestamp for the original file    -   4) initial storage location of the original file    -   5) blockchain network member ID for software to currently        control the original file and associated metadata

The other blocks 778 ₂ to 778 _(N) in the blockchain also have headers,files, and values. However, unlike the first block 772 ₁, each of theheaders 772 ₂ to 772 _(N) in the other blocks includes the hash value ofan immediately preceding block. The hash value of the immediatelypreceding block may be just the hash of the header of the previous blockor may be the hash value of the entire previous block. By including thehash value of a preceding block in each of the remaining blocks, a tracecan be performed from the Nth block back to the genesis block (and theassociated original file) on a block-by-block basis, as indicated byarrows 780, to establish an auditable and immutable chain-of-custody.

Each of the header 772 ₂ to 772 _(N) in the other blocks may alsoinclude other information, e.g., version number, timestamp, nonce, rootinformation, difficulty level, consensus protocol, and/or otherparameters or information associated with the corresponding files and/orthe blockchain in general.

The files 774 ₂ to 774 _(N) in the other blocks may be equal to theoriginal file or may be a modified version of the original file in thegenesis block depending, for example, on the type of processingperformed. The type of processing performed may vary from block toblock. The processing may involve, for example, any modification of afile in a preceding block, such as redacting information or otherwisechanging the content of, taking information away from, or adding orappending information to the files.

Additionally, or alternatively, the processing may involve merelycopying the file from a preceding block, changing a storage location ofthe file, analyzing the file from one or more preceding blocks, movingthe file from one storage or memory location to another, or performingaction relative to the file of the blockchain and/or its associatedmetadata. Processing which involves analyzing a file may include, forexample, appending, including, or otherwise associating variousanalytics, statistics, or other information associated with the file.

The values in each of the other blocks 776 ₂ to 776 _(N) in the otherblocks are unique values and are all different as a result of theprocessing performed. For example, the value in any one blockcorresponds to an updated version of the value in the previous block.The update is reflected in the hash of the block to which the value isassigned. The values of the blocks therefore provide an indication ofwhat processing was performed in the blocks and also permit a tracingthrough the blockchain back to the original file. This tracking confirmsthe chain-of-custody of the file throughout the entire blockchain.

For example, consider the case where portions of the file in a previousblock are redacted, blocked out, or pixelated in order to protect theidentity of a person shown in the file. In this case, the blockincluding the redacted file will include metadata associated with theredacted file, e.g., how the redaction was performed, who performed theredaction, timestamps where the redaction(s) occurred, etc. The metadatamay be hashed to form the value. Because the metadata for the block isdifferent from the information that was hashed to form the value in theprevious block, the values are different from one another and may berecovered when decrypted.

In one embodiment, the value of a previous block may be updated (e.g., anew hash value computed) to form the value of a current block when anyone or more of the following occurs. The new hash value may be computedby hashing all or a portion of the information noted below, in thisexample embodiment.

-   -   a) new SHA-2 computed hash value if the file has been processed        in any way (e.g., if the file was redacted, copied, altered,        accessed, or some other action was taken)    -   b) new storage location for the file    -   c) new metadata identified associated with the file    -   d) transfer of access or control of the file from one blockchain        participant to another blockchain participant

FIG. 7D illustrates an embodiment of a block which may represent thestructure of the blocks in the blockchain 790 in accordance with oneembodiment. The block, Block_(i), includes a header 772 _(i), a file 774_(i), and a value 776 _(i).

The header 772 ₁ includes a hash value of a previous block Block_(i-1)and additional reference information, which, for example, may be any ofthe types of information (e.g., header information including references,characteristics, parameters, etc.) discussed herein. All blocksreference the hash of a previous block except, of course, the genesisblock. The hash value of the previous block may be just a hash of theheader in the previous block or a hash of all or a portion of theinformation in the previous block, including the file and metadata.

The file 774 ₁ includes a plurality of data, such as Data 1, Data 2, . .. , Data N in sequence. The data are tagged with Metadata 1, Metadata 2,. . . , Metadata N which describe the content and/or characteristicsassociated with the data. For example, the metadata for each data mayinclude information to indicate a timestamp for the data, process thedata, keywords indicating the persons or other content depicted in thedata, and/or other features that may be helpful to establish thevalidity and content of the file as a whole, and particularly its use adigital evidence, for example, as described in connection with anembodiment discussed below. In addition to the metadata, each data maybe tagged with reference REF₁, REF₂, . . . , REF_(N) to a previous datato prevent tampering, gaps in the file, and sequential reference throughthe file.

Once the metadata is assigned to the data (e.g., through a smartcontract), the metadata cannot be altered without the hash changing,which can easily be identified for invalidation. The metadata, thus,creates a data log of information that may be accessed for use byparticipants in the blockchain.

The value 776 _(i) is a hash value or other value computed based on anyof the types of information previously discussed. For example, for anygiven block Block_(i), the value for that block may be updated toreflect the processing that was performed for that block, e.g., new hashvalue, new storage location, new metadata for the associated file,transfer of control or access, identifier, or other action orinformation to be added. Although the value in each block is shown to beseparate from the metadata for the data of the file and header, thevalue may be based, in part or whole, on this metadata in anotherembodiment.

Once the blockchain 770 is formed, at any point in time, the immutablechain-of-custody for the file may be obtained by querying the blockchainfor the transaction history of the values across the blocks. This query,or tracking procedure, may begin with decrypting the value of the blockthat is most currently included (e.g., the last (N^(th)) block), andthen continuing to decrypt the value of the other blocks until thegenesis block is reached and the original file is recovered. Thedecryption may involve decrypting the headers and files and associatedmetadata at each block, as well.

Decryption is performed based on the type of encryption that took placein each block. This may involve the use of private keys, public keys, ora public key-private key pair. For example, when asymmetric encryptionis used, blockchain participants or a processor in the network maygenerate a public key and private key pair using a predeterminedalgorithm. The public key and private key are associated with each otherthrough some mathematical relationship. The public key may bedistributed publicly to serve as an address to receive messages fromother users, e.g., an IP address or home address. The private key iskept secret and used to digitally sign messages sent to other blockchainparticipants. The signature is included in the message so that therecipient can verify using the public key of the sender. This way, therecipient can be sure that only the sender could have sent this message.

Generating a key pair may be analogous to creating an account on theblockchain, but without having to actually register anywhere. Also,every transaction that is executed on the blockchain is digitally signedby the sender using their private key. This signature ensures that onlythe owner of the account can track and process (if within the scope ofpermission determined by a smart contract) the file of the blockchain.

FIGS. 8A and 8B illustrate additional examples of use cases forblockchain which may be incorporated and used herein. In particular,FIG. 8A illustrates an example 800 of a blockchain 810 which storesmachine learning (artificial intelligence) data. Machine learning relieson vast quantities of historical data (or training data) to buildpredictive models for accurate prediction on new data. Machine learningsoftware (e.g., neural networks, etc.) can often sift through millionsof records to unearth non-intuitive patterns.

In the example of FIG. 8A, a host platform 820 builds and deploys amachine learning model for predictive monitoring of assets 830. Here,the host platform 820 may be a cloud platform, an industrial server, aweb server, a personal computer, a user device, and the like. Assets 830can be any type of asset (e.g., machine or equipment, etc.) such as anaircraft, locomotive, turbine, medical machinery and equipment, oil andgas equipment, boats, ships, vehicles, and the like. As another example,assets 830 may be non-tangible assets such as stocks, currency, digitalcoins, insurance, or the like.

The blockchain 810 can be used to significantly improve both a trainingprocess 802 of the machine learning model and a predictive process 804based on a trained machine learning model. For example, in 802, ratherthan requiring a data scientist/engineer or other user to collect thedata, historical data may be stored by the assets 830 themselves (orthrough an intermediary, not shown) on the blockchain 810. This cansignificantly reduce the collection time needed by the host platform 820when performing predictive model training. For example, using smartcontracts, data can be directly and reliably transferred straight fromits place of origin to the blockchain 810. By using the blockchain 810to ensure the security and ownership of the collected data, smartcontracts may directly send the data from the assets to the individualsthat use the data for building a machine learning model. This allows forsharing of data among the assets 830.

The collected data may be stored in the blockchain 810 based on aconsensus mechanism. The consensus mechanism pulls in (permissionednodes) to ensure that the data being recorded is verified and accurate.The data recorded is time-stamped, cryptographically signed, andimmutable. It is therefore auditable, transparent, and secure. AddingIoT devices which write directly to the blockchain can, in certain cases(i.e. supply chain, healthcare, logistics, etc.), increase both thefrequency and accuracy of the data being recorded.

Furthermore, training of the machine learning model on the collecteddata may take rounds of refinement and testing by the host platform 820.Each round may be based on additional data or data that was notpreviously considered to help expand the knowledge of the machinelearning model. In 802, the different training and testing steps (andthe data associated therewith) may be stored on the blockchain 810 bythe host platform 820. Each refinement of the machine learning model(e.g., changes in variables, weights, etc.) may be stored on theblockchain 810. This provides verifiable proof of how the model wastrained and what data was used to train the model. Furthermore, when thehost platform 820 has achieved a finally trained model, the resultingmodel may be stored on the blockchain 810.

After the model has been trained, it may be deployed to a liveenvironment where it can make predictions/decisions based on theexecution of the final trained machine learning model. For example, in804, the machine learning model may be used for condition-basedmaintenance (CBM) for an asset such as an aircraft, a wind turbine, ahealthcare machine, and the like. In this example, data fed back fromthe asset 830 may be input the machine learning model and used to makeevent predictions such as failure events, error codes, and the like.Determinations made by the execution of the machine learning model atthe host platform 820 may be stored on the blockchain 810 to provideauditable/verifiable proof. As one non-limiting example, the machinelearning model may predict a future breakdown/failure to a part of theasset 830 and create alert or a notification to replace the part. Thedata behind this decision may be stored by the host platform 820 on theblockchain 810. In one embodiment the features and/or the actionsdescribed and/or depicted herein can occur on or with respect to theblockchain 810.

New transactions for a blockchain can be gathered together into a newblock and added to an existing hash value. This is then encrypted tocreate a new hash for the new block. This is added to the next list oftransactions when they are encrypted, and so on. The result is a chainof blocks that each contain the hash values of all preceding blocks.Computers that store these blocks regularly compare their hash values toensure that they are all in agreement. Any computer that does not agree,discards the records that are causing the problem. This approach is goodfor ensuring tamper-resistance of the blockchain, but it is not perfect.

One way to game this system is for a dishonest user to change the listof transactions in their favor, but in a way that leaves the hashunchanged. This can be done by brute force, in other words by changing arecord, encrypting the result, and seeing whether the hash value is thesame. And if not, trying again and again and again until it finds a hashthat matches. The security of blockchains is based on the belief thatordinary computers can only perform this kind of brute force attack overtime scales that are entirely impractical, such as the age of theuniverse. By contrast, quantum computers are much faster (1000s of timesfaster) and consequently pose a much greater threat.

FIG. 8B illustrates an example 850 of a quantum-secure blockchain 852which implements quantum key distribution (QKD) to protect against aquantum computing attack. In this example, blockchain users can verifyeach other's identities using QKD. This sends information using quantumparticles such as photons, which cannot be copied by an eavesdropperwithout destroying them. In this way, a sender and a receiver throughthe blockchain can be sure of each other's identity.

In the example of FIG. 8B, four users are present 854, 856, 858, and860. Each of pair of users may share a secret key 862 (i.e., a QKD)between themselves. Since there are four nodes in this example, sixpairs of nodes exists, and therefore six different secret keys 862 areused including QKD_(AB), QKD_(AC), QKD_(AD), QKD_(BC), QKD_(BD), andQKD_(CD). Each pair can create a QKD by sending information usingquantum particles such as photons, which cannot be copied by aneavesdropper without destroying them. In this way, a pair of users canbe sure of each other's identity.

The operation of the blockchain 852 is based on two procedures (i)creation of transactions, and (ii) construction of blocks that aggregatethe new transactions. New transactions may be created similar to atraditional blockchain network. Each transaction may contain informationabout a sender, a receiver, a time of creation, an amount (or value) tobe transferred, a list of reference transactions that justifies thesender has funds for the operation, and the like. This transactionrecord is then sent to all other nodes where it is entered into a poolof unconfirmed transactions. Here, two parties (i.e., a pair of usersfrom among 854-860) authenticate the transaction by providing theirshared secret key 862 (QKD). This quantum signature can be attached toevery transaction making it exceedingly difficult to tamper with. Eachnode checks their entries with respect to a local copy of the blockchain852 to verify that each transaction has sufficient funds. However, thetransactions are not yet confirmed.

Rather than perform a traditional mining process on the blocks, theblocks may be created in a decentralized manner using a broadcastprotocol. At a predetermined period of time (e.g., seconds, minutes,hours, etc.) the network may apply the broadcast protocol to anyunconfirmed transaction thereby to achieve a Byzantine agreement(consensus) regarding a correct version of the transaction. For example,each node may possess a private value (transaction data of thatparticular node). In a first round, nodes transmit their private valuesto each other. In subsequent rounds, nodes communicate the informationthey received in the previous round from other nodes. Here, honest nodesare able to create a complete set of transactions within a new block.This new block can be added to the blockchain 852. In one embodiment thefeatures and/or the actions described and/or depicted herein can occuron or with respect to the blockchain 852.

FIG. 9 illustrates an example system 900 that supports one or more ofthe example embodiments described and/or depicted herein. The system 900comprises a computer system/server 902, which is operational withnumerous other general purpose or special purpose computing systemenvironments or configurations. Examples of well-known computingsystems, environments, and/or configurations that may be suitable foruse with computer system/server 902 include, but are not limited to,personal computer systems, server computer systems, thin clients, thickclients, hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network PCs, minicomputer systems, mainframe computersystems, and distributed cloud computing environments that include anyof the above systems or devices, and the like.

Computer system/server 902 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 902 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 9 , computer system/server 902 in cloud computing node900 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 902 may include, but are notlimited to, one or more processors or processing units 904, a systemmemory 906, and a bus that couples various system components includingsystem memory 906 to processor 904.

The bus represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

Computer system/server 902 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 902, and it includes both volatileand non-volatile media, removable and non-removable media. System memory906, in one embodiment, implements the flow diagrams of the otherfigures. The system memory 906 can include computer system readablemedia in the form of volatile memory, such as random-access memory (RAM)910 and/or cache memory 912. Computer system/server 902 may furtherinclude other removable/non-removable, volatile/non-volatile computersystem storage media. By way of example only, storage system 914 can beprovided for reading from and writing to a non-removable, non-volatilemagnetic media (not shown and typically called a “hard drive”). Althoughnot shown, a magnetic disk drive for reading from and writing to aremovable, non-volatile magnetic disk (e.g., a “floppy disk”), and anoptical disk drive for reading from or writing to a removable,non-volatile optical disk such as a CD-ROM, DVD-ROM or other opticalmedia can be provided. In such instances, each can be connected to thebus by one or more data media interfaces. As will be further depictedand described below, memory 906 may include at least one program producthaving a set (e.g., at least one) of program modules that are configuredto carry out the functions of various embodiments of the application.

Program/utility 916, having a set (at least one) of program modules 918,may be stored in memory 906 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 918 generally carry out the functionsand/or methodologies of various embodiments of the application asdescribed herein.

As will be appreciated by one skilled in the art, aspects of the presentapplication may be embodied as a system, method, or computer programproduct. Accordingly, aspects of the present application may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present application may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Computer system/server 902 may also communicate with one or moreexternal devices 920 such as a keyboard, a pointing device, a display922, etc.; one or more devices that enable a user to interact withcomputer system/server 902; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 902 to communicate withone or more other computing devices. Such communication can occur viaI/O interfaces 924. Still yet, computer system/server 902 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 926. As depicted, network adapter 926communicates with the other components of computer system/server 902 viaa bus. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 902. Examples include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Although an exemplary embodiment of at least one of a system, method,and non-transitory computer readable medium has been illustrated in theaccompanied drawings and described in the foregoing detaileddescription, it will be understood that the application is not limitedto the embodiments disclosed, but is capable of numerous rearrangements,modifications, and substitutions as set forth and defined by thefollowing claims. For example, the capabilities of the system of thevarious figures can be performed by one or more of the modules orcomponents described herein or in a distributed architecture and mayinclude a transmitter, receiver or pair of both. For example, all orpart of the functionality performed by the individual modules, may beperformed by one or more of these modules. Further, the functionalitydescribed herein may be performed at various times and in relation tovarious events, internal or external to the modules or components. Also,the information sent between various modules can be sent between themodules via at least one of: a data network, the Internet, a voicenetwork, an Internet Protocol network, a wireless device, a wired deviceand/or via plurality of protocols. Also, the messages sent or receivedby any of the modules may be sent or received directly and/or via one ormore of the other modules.

One skilled in the art will appreciate that a “system” could be embodiedas a personal computer, a server, a console, a personal digitalassistant (PDA), a cell phone, a tablet computing device, a smartphoneor any other suitable computing device, or combination of devices.Presenting the above-described functions as being performed by a“system” is not intended to limit the scope of the present applicationin any way but is intended to provide one example of many embodiments.Indeed, methods, systems and apparatuses disclosed herein may beimplemented in localized and distributed forms consistent with computingtechnology.

It should be noted that some of the system features described in thisspecification have been presented as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom verylarge-scale integration (VLSI) circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. A module may also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, graphics processing units, or thelike.

A module may also be at least partially implemented in software forexecution by various types of processors. An identified unit ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions that may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified module need not be physically locatedtogether but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the module andachieve the stated purpose for the module. Further, modules may bestored on a computer-readable medium, which may be, for instance, a harddisk drive, flash device, random access memory (RAM), tape, or any othersuch medium used to store data.

Indeed, a module of executable code could be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within modules and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork.

It will be readily understood that the components of the application, asgenerally described and illustrated in the figures herein, may bearranged and designed in a wide variety of different configurations.Thus, the detailed description of the embodiments is not intended tolimit the scope of the application as claimed but is merelyrepresentative of selected embodiments of the application.

One having ordinary skill in the art will readily understand that theabove may be practiced with steps in a different order, and/or withhardware elements in configurations that are different than those whichare disclosed. Therefore, although the application has been describedbased upon these preferred embodiments, it would be apparent to those ofskill in the art that certain modifications, variations, and alternativeconstructions would be apparent.

While preferred embodiments of the present application have beendescribed, it is to be understood that the embodiments described areillustrative only and the scope of the application is to be definedsolely by the appended claims when considered with a full range ofequivalents and modifications (e.g., protocols, hardware devices,software platforms etc.) thereto.

What is claimed is:
 1. An apparatus comprising: a processor configuredto generate a single verifiable credential (VC) for an entire blockchainin a blockchain network, wherein the processor is configured to:retrieve decentralized identifiers (DIDs) of all of the blockchain peersincluded within the blockchain network; generate a blockchaindeclarative descriptor (BDD) that uniquely identifies the blockchainnetwork, the BDD comprising: a first field including the DIDs, a secondfield that includes combined signature data of all of the blockchainpeers, and a third field that includes metadata; transmit the BDD to ablockchain network registry; receive a single document that all of theblockchain peers have signed; store the single document within thesecond field of the BDD; and utilize the VC to prove that a blockchainpeer, of all of the blockchain peers, participates within the blockchainnetwork.
 2. The apparatus of claim 1, wherein the processor is furtherconfigured to: receive a plurality of documents from corresponding onesof the plurality of blockchain peers, where each document, of theplurality of documents, is signed by a different correspondingblockchain peer; and store the plurality of documents within the secondfield of the BDD.
 3. The apparatus of claim 1, wherein the processor isfurther configured to: store a blockchain network updation descriptorwithin the first field of the BDD.
 4. The apparatus of claim 1, wherein,when the processor retrieves the DIDs, the processor is furtherconfigured to: retrieve the DIDs from a registry that stores a mappingbetween a unique identifier of a blockchain peer and a corresponding DIDof that blockchain peer.
 5. The apparatus of claim 1, wherein theblockchain network registry maps a name of the blockchain network to itscorresponding BDD.
 6. The apparatus of claim 1, wherein the processor isfurther configured to: detect a new blockchain peer within theblockchain network; update the first field of the BDD to include a DIDof the new blockchain peer; and update the second field to include asignature of the new blockchain peer.
 7. The apparatus of claim 1,wherein the processor is further configured to: identify a chaincodeinstalled within the blockchain network; and storing a name of thechaincode within the first field of the BDD.
 8. A method for generatinga single verifiable credential (VC) for an entire blockchain in ablockchain network, the method comprising: retrieving decentralizedidentifiers (DIDs) of all of the blockchain peers included within theblockchain network; generating a blockchain declarative descriptor (BDD)that uniquely identifies the blockchain network, the BDD comprising: afirst field including the DIDs, a second field including combinedsignature data of all of the blockchain peers, and a third fieldincluding metadata; transmitting the BDD to a blockchain networkregistry; receiving a single document that all of the blockchain peershave signed; storing the single document within the second field of theBDD; and utilizing the VC to prove that a blockchain peer, of all of theblockchain peers, participates within the blockchain network.
 9. Themethod of claim 8, further comprising: receiving a plurality ofdocuments from corresponding ones of the plurality of blockchain peers,where each document, of the plurality of documents, is signed by adifferent corresponding blockchain peer; and storing the plurality ofdocuments within the second field of the BDD.
 10. The method of claim 8,further comprising: storing a blockchain network updation descriptorwithin the first field of the BDD.
 11. The method of claim 8, whereinthe retrieving the DIDs further comprises: retrieving the DIDs from aregistry that stores a mapping between a unique identifier of ablockchain peer and a corresponding DID of that blockchain peer.
 12. Themethod of claim 8, wherein the blockchain network registry maps a nameof the blockchain network to its corresponding BDD.
 13. The method ofclaim 8, further comprising: detecting a new blockchain peer within theblockchain network; updating the first field of the BDD to include a DIDof the new blockchain peer; and updating the second field to include asignature of the new blockchain peer.
 14. The method of claim 8, furthercomprising: identifying a chaincode installed within the blockchainnetwork; and storing a name of the chaincode within the first field ofthe BDD.